U.S. patent number 8,792,942 [Application Number 12/874,195] was granted by the patent office on 2014-07-29 for base station device, communication system, and control method of tilt angle of antenna.
This patent grant is currently assigned to Fujitsu Limited. The grantee listed for this patent is Teppei Oyama. Invention is credited to Teppei Oyama.
United States Patent |
8,792,942 |
Oyama |
July 29, 2014 |
Base station device, communication system, and control method of
tilt angle of antenna
Abstract
A base station device includes a first antenna which transmits a
radio signal in a downlink, a second antenna which receives a radio
signal in an uplink, and a tilt angle control unit which controls a
tilt angle of the first antenna and the second antenna to decrease
a difference in a position of a cell boundary of the downlink and a
position of the cell boundary of the uplink based on a
communication quality of the downlink and a communication quality
of the uplink with respect to a first base station device and on
the communication quality of a downlink and a communication quality
of the uplink with respect to an adjacent second base station
device.
Inventors: |
Oyama; Teppei (Kawasaki,
JP) |
Applicant: |
Name |
City |
State |
Country |
Type |
Oyama; Teppei |
Kawasaki |
N/A |
JP |
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Assignee: |
Fujitsu Limited (Kawasaki,
JP)
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Family
ID: |
43625679 |
Appl.
No.: |
12/874,195 |
Filed: |
September 1, 2010 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20110053647 A1 |
Mar 3, 2011 |
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Foreign Application Priority Data
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Sep 2, 2009 [JP] |
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2009-202712 |
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Current U.S.
Class: |
455/562.1;
455/575.7 |
Current CPC
Class: |
H04W
16/28 (20130101); H04W 72/085 (20130101) |
Current International
Class: |
H04M
1/00 (20060101) |
Field of
Search: |
;455/562.1,575.7 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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2007-28091 |
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Feb 2007 |
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JP |
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2007-514367 |
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May 2007 |
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JP |
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2008-141741 |
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Jun 2008 |
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JP |
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Primary Examiner: Patel; Mahendra
Assistant Examiner: Plata; Edd Rianne
Attorney, Agent or Firm: Fujitsu Patent Center
Claims
What is claimed is:
1. A base station device, comprising: a first antenna which
transmits a radio signal in a downlink; a second antenna which
receives a radio signal in an uplink; and a tilt angle control unit
which controls a tilt angle of the first antenna and the second
antenna to decrease a difference in a position of a cell boundary
of the downlink and a position of the cell boundary of the uplink
based on a first downlink communication quality and a first uplink
communication quality with respect to a first base station device
and on a second downlink communication quality and a second uplink
communication quality with respect to an adjacent second base
station device, wherein the tilt angle control unit groups mobile
stations receiving communications from the first base station
device and the adjacent second base station device into a first
group, in which a highest communication quality of the downlink is
measured based on reception power, and a second group, in which the
highest communication quality of the uplink is measured based on
reception power, compares a number of mobile stations in the first
group and a number of mobile station in the second group, and
controls the tilt angle of the first antenna or the second antenna
to decrease a mismatch between the number of mobile stations in the
first group and the number of mobile stations in the second group,
wherein the tilt angle control unit further determines whether a
cell boundary of the downlink or a cell boundary of the uplink is
closer to the first base station device based on the comparison of
the number of mobile stations between the first group and the
number of mobile stations in the second group.
2. The base station device according to claim 1, wherein the tilt
angle control unit controls the tilt angle of the first antenna to
decrease the difference between: a) the first downlink
communication quality between a communication device positioned in
a prescribed position and the first base station device and b) the
second downlink communication quality between the communication
device and the second base station device.
3. The base station device according to claim 1, wherein the tilt
angle control unit controls the tilt angle of the second antenna to
decrease the difference between: a) the first uplink communication
quality between the communication device positioned in the
prescribed position and the first base station device and b) the
second uplink communication quality between the communication
device and the second base station device.
4. The base station device according to claim 1, wherein the tilt
angle control unit controls the tilt angle of the first antenna or
the second antenna to decrease the difference between: a) the first
uplink communication quality between a mobile station which
performs handover processing and the first base station device and
b) the second uplink communication quality between the mobile
station and the adjacent second base station device.
5. The base station device according to any of claims 1 to 4,
wherein the tilt angle control unit controls a tilt angle of the
first antenna and the second antenna to decrease the difference
between a) the cell boundary of the downlink and the cell boundary
of the uplink between the first base station device and b) the
adjacent second base station device.
6. A communication system, comprising: a base station including, a
first antenna which transmits a radio signal in a downlink; a
second antenna which receives a radio signal in an uplink; and a
tilt angle control unit which controls a tilt angle of the first
antenna and the second antenna to decrease a difference of a cell
boundary between the downlink and the uplink based on a first
downlink communication quality and a first uplink communication
quality with respect to a first base station device and on a second
downlink communication quality and a second uplink communication
quality with respect to an adjacent second base station device; and
a mobile station which communicates with the base station
including, a reference signal transmission unit which transmits a
reference signal of a communication quality measurement in the
uplink, wherein the tilt angle control unit groups mobile stations
receiving communications from the first base station device and the
adjacent second base station device into a first group, in which a
highest communication quality of the downlink is measured based on
reception power, and a second group, in which the highest
communication quality of the uplink is measured based on reception
power, compares a number of mobile stations in the first group and
a number of mobile station in the second group, and controls the
tilt angle of the first antenna or the second antenna to decrease a
mismatch between the number of mobile stations in the first group
and the number of mobile stations in the second group, wherein the
tilt angle control unit further determines whether a cell boundary
of the downlink or a cell boundary of the uplink is closer to the
first base station device based on the comparison of the number of
mobile stations between the first group and the number of mobile
stations in the second group.
7. The communication system according to claim 6, wherein the
reference signal transmission unit transmits the reference signal
when the mobile station performs the handover processing.
8. A control method for controlling a tilt angle of a first antenna
and a second antenna, provided in a first base station device, used
for transmitting a radio signal in a downlink and for receiving a
radio signal in an uplink, the control method comprising: measuring
a first downlink communication quality and a first uplink quality
with respect to the first base station device and a second downlink
communication quality and a second uplink communication quality
with respect to an adjacent second base station device; grouping
mobile stations receiving communications from the first base
station device and the adjacent second base station device into a
first group, in which a highest communication quality of the
downlink is measured based on reception power, and a second group,
in which the highest communication quality of the uplink is
measured based on reception power; comparing a number of mobile
stations in the first group and a number of mobile station in the
second group; controlling the tilt angle of the first antenna or
the second antenna to decrease a mismatch between the number of
mobile stations in the first group and the number of mobile
stations in the second group; and determining whether a cell
boundary of the downlink or a cell boundary of the uplink is closer
to the first base station device based on the comparison of the
number of mobile stations between the first group and the number of
mobile stations in the second group.
9. The control method according to claim 8, further comprising
controlling the tilt angle of the first antenna to decrease the
difference between: a) the first downlink communication quality
between a communication device positioned in a prescribed position
and the first base station device and b) the second downlink
communication quality between the communication device and the
second base station device.
10. The control method according to claim 8, further comprising
controlling the tilt angle of the second antenna to decrease the
difference between: a) the first uplink communication quality
between the communication device positioned in the prescribed
position and the first base station device and b) the second uplink
communication quality between the communication device and the
second base station device.
11. The control method according to claim 9, further comprising
controlling a tilt angle of the first antenna and the second
antenna to decrease the difference between a) the cell boundary of
the downlink and the cell boundary of the uplink between the first
base station device and b) the adjacent second base station
device.
12. The control method according to claim 8, further comprising
controlling the tilt angle of the first antenna or the second
antenna to decrease the difference between: a) the first uplink
communication quality between a mobile station which performs
handover processing and the first base station device and b) the
second uplink communication quality between the mobile station and
the adjacent second base station device.
13. The control method according to claim 12, further comprising
controlling a tilt angle of the first antenna and the second
antenna to decrease the difference between a) the cell boundary of
the downlink and the cell boundary of the uplink between the first
base station device and b) the adjacent second base station
device.
14. The control method according to claim 8, wherein the
controlling reduces a difference in a position of a cell boundary
of the downlink and the uplink between the first base station
device and the adjacent second base station device.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is based upon and claims the benefit of priority
from the prior Japanese Patent Application No. 2009-202712 filed on
Sep. 2, 2009, the entire contents of which are incorporated herein
by reference.
FIELD
The embodiments discussed herein relate to a base station device, a
communication system, and a control method of a tilt angle of an
antenna in a radio communication system.
BACKGROUND
In a mobile cellular network, geological communicable areas are
divided into many cells, and each of the cells corresponds to a
single base station. When power is supplied to a mobile station,
the mobile station searches for a base station as a communication
destination. In most cases, a cell search function is performed
based on a cell-specific reference signal, which is periodically
transmitted, or a preamble signal. In a basic method, the search is
comprehensively performed by detecting all reference signals and
then acquiring the best base station, based on some given criteria
or factors, to serve as a communication destination.
There is a proposed method used in a mobile communication system in
which a macrocell comprises a smaller microcell (see, for example,
Japanese Laid-open Patent Publication No. 2007-514367). The
above-described method includes a process for establishing an
uplink communication cell boundary between a macrocell and a
microcell, and a process for establishing a downlink communication
cell boundary differently from the uplink communication cell
boundary between the macrocell and the microcell. The uplink
communication cell boundary is established to be wider than the
downlink communication cell boundary. The downlink communication
cell boundary is established by inclining a downlink antenna beam
of the base station in association with the microcell transmitting
a broadcast signal and by reducing a coverage area of the broadcast
signal.
There is a proposed base station that includes a plurality of tilt
beam antennas to cover substantially the same communication area
and a beam tilt angle control unit that changes a tilt angle of at
least one of the tilt beam antennas to make the tilt angle
different from the tilt angles of the other beam antennas. The
above-described base station performs rake combining on a level
received by using at least two tilt beam antennas on an uplink line
and transmits signals by using at least one tilt beam antenna with
a higher reception level on a downlink line (see, for example,
Japanese Laid-open Patent Publication No. 2007-28091).
With which cell the mobile station prefers to communicate differs
according to whether the signal is the uplink or the downlink. The
above-described state may be called "uplink-and-downlink asymmetric
state."
The uplink-and-downlink asymmetric state may occur if, for example,
the base station devices, which are arranged respectively in the
adjacent cells, have different transmission power. Here, it is
assumed that the base station devices having different transmission
power are arranged in the adjacent two cells and that the mobile
station is positioned in a position that is slightly closer to the
base station device whose transmission power is relatively small
than the base station device whose transmission power is relatively
large. In this case, as for the downlink, reception power received
from the base station device whose transmission power is relatively
large is larger than the reception power of the base station device
whose transmission power is relatively small. Therefore, it is
preferable that the mobile station communicates with the base
station device whose transmission power is relatively large.
On the other hand, as for the uplink, the base station device,
which is closer to the mobile station and has the relatively small
transmission power, has the reception power that is larger than the
reception power of the base station device whose transmission power
is relatively large. Accordingly, it is preferable that the mobile
station communicates with the base station device whose
transmission power is relatively small.
If the uplink-and-downlink asymmetric state occurs, interference
power received by the other cell is larger than the reception power
of the uplink received by the communicating cell. This may cause
deterioration of the communication quality in the uplink.
SUMMARY
According to an aspect of the invention, a base station device
includes a first antenna which transmits a radio signal in a
downlink, a second antenna which receives a radio signal in an
uplink, and a tilt angle control unit which controls a tilt angle
of the first antenna and the second antenna to decrease a
difference in a position of a cell boundary of the downlink and a
position of the cell boundary of the uplink based on a
communication quality of the downlink and a communication quality
of the uplink with respect to a first base station device and on
the communication quality of a downlink and a communication quality
of the uplink with respect to an adjacent second base station
device.
The object and advantages of the invention will be realized and
attained by at least the features, elements, and combinations
particularly pointed out in the claims.
It is to be understood that both the foregoing general description
and the following detailed description are exemplary and
explanatory and are not restrictive of the invention, as
claimed.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a configuration diagram of an embodiment of a base
station device,
FIG. 2 is an explanation diagram of an embodiment of a control
method of a tilt angle,
FIG. 3 is a configuration diagram of a first embodiment of a radio
communication system,
FIG. 4 is a diagram illustrating a first example of a configuration
of a base station device illustrated in FIG. 3,
FIG. 5 is a diagram illustrating a configuration example of a
communication device illustrated in FIG. 3,
FIG. 6 is a diagram illustrating a configuration example of a tilt
angle control unit illustrated in FIG. 4,
FIG. 7 is an explanation diagram of a control example of a tilt
angle of a transmission antenna in the radio communication system
illustrated in FIG. 3,
FIG. 8 is a diagram illustrating a second example of the
configuration of the base station device illustrated in FIG. 3,
FIG. 9 is a configuration diagram of a second embodiment of the
radio communication system,
FIG. 10 is a diagram illustrating a configuration example of a
communication device illustrated in FIG. 9,
FIG. 11 is a diagram illustrating a configuration example of a base
station device illustrated in FIG. 9,
FIG. 12 is an explanation diagram of a control example of a tilt
angle of a reception antenna in a radio communication system
illustrated in FIG. 9,
FIG. 13 is a configuration diagram of a third embodiment of the
radio communication system,
FIG. 14 is a diagram illustrating a configuration example of a base
station device illustrated in FIG. 13,
FIG. 15 is a diagram illustrating a configuration example of a
communication device illustrated in FIG. 13,
FIG. 16 is an explanation diagram of a control example of a tilt
angle of a reception antenna in the radio communication system
illustrated in FIG. 13,
FIG. 17 is a configuration diagram of a fourth embodiment of a
radio communication system,
FIG. 18 is a diagram illustrating a configuration example of a
mobile station illustrated in FIG. 17,
FIG. 19 is a diagram illustrating a configuration example of a base
station device illustrated in FIG. 17,
FIG. 20 is a diagram illustrating a configuration example of a tilt
angle control unit illustrated in FIG. 19,
FIG. 21 is an explanation diagram of an example of correspondence
relation information,
FIG. 22 is an explanation diagram of a control example of a tilt
angle of an antenna in the radio communication system illustrated
in FIG. 17,
FIG. 23 is a configuration diagram of a fifth embodiment of the
radio communication system,
FIG. 24 is a diagram illustrating a configuration example of a
mobile station device illustrated in FIG. 23,
FIG. 25 is a diagram illustrating a configuration example of a base
station device illustrated in FIG. 23, and
FIG. 26 is an explanation diagram of a control example of a tilt
angle of an antenna in the radio communication system illustrated
in FIG. 23.
DESCRIPTION OF EMBODIMENTS
With reference to the attached diagrams, description will be made
of embodiments of the present invention. FIG. 1 is a configuration
diagram of an embodiment of a base station device. Reference
numeral 10 indicates a base station device. Reference numeral 11
indicates a transmission antenna. Reference numeral 12 indicates a
reception antenna. Reference numeral 13 and reference numeral 14
indicate tilt angle changing units. Reference numeral 15 indicates
a tilt angle control unit.
The base station device 10 includes the transmission antenna 11,
the reception antenna 12, the tilt angle changing units 13 and 14,
and the tilt angle control unit 15. The transmission antenna 11
transmits, from the base station device 10, a radio signal in a
downlink transmitted to a mobile station, for example. The
reception antenna 12 receives a radio signal in an uplink
transmitted to the base station device 10 from, e.g. the mobile
station. The transmission antenna 11 and the reception antenna 12
are given as an example of a first antenna and a second antenna,
respectively; however, the base station device 10 may include one
or more of each of a transmission antenna 11 and reception antenna
12.
The tilt angle changing units 13 and 14 change the tilt angle of a
main beam of an antenna gain pattern of the transmission antenna 11
and the reception antenna 12, respectively. In this case, the "tilt
angle" may be a depression angle, which is an angle between a
vertical in-plane direction and the horizontal direction of the
main beam of the antenna gain pattern of the transmission antenna
11 and the reception antenna 12. For simple description, the tilt
angle of the main beam of the antenna gain pattern of the
transmission antenna 11 and the reception antenna 12 may be
described as the tilt angle of the transmission antenna 11 and the
reception antenna 12, respectively.
As described below, the tilt angle control unit 15 controls at
least either of the tilt angle of the transmission antenna 11 and
the tilt angle of the reception antenna 12 by controlling at least
either of the tilt angle changing unit 13 and the tilt angle
changing unit 14.
FIG. 2 is an explanation diagram of an embodiment of a control
method of a tilt angle. In Operation AA, a communication quality of
the downlink between the base station device 10 and each of the
other base station devices, which are arranged in a cell that is
adjacent to the cell in which the base station device 10 is
arranged, is measured. For convenience of the description, the
other base station device arranged in the adjacent cell may be
described as an "adjacent base station device."
For example, by receiving the radio signal transmitted from each of
the base station device 10 and the adjacent base station device,
the mobile station or the other communication device may measure
the communication quality of the downlink with respect to the base
station device 10 and the adjacent base station device.
In Operation AB, the communication quality of the uplink is
measured with respect to the base station device 10 and the
adjacent base station device, respectively. For example, by
receiving the radio signal transmitted from the mobile station
device or the other communication device, the base station device
or the other communication device may measure the communication
quality of the downlink with respect to the base station device and
the other base station device, respectively.
Alternatively, for example, by receiving each of the radio signals
transmitted from the base station device 10 and the adjacent base
station device, the mobile station or the communication device may
measure the communication quality of the downlink with respect to
the base station device 10 and the adjacent base station device,
respectively. In this case, the communication quality of the
downlink may be determined based on transmission loss obtained by
subtracting the reception power measured by the mobile station or
the communication device from the known transmission power of the
base station device 10 or the adjacent base station device. Either
of Operation AA and Operation AB may be performed first.
In Operation AC, the tilt angle control unit 15 controls at least
either of the tilt angle of the transmission antenna 11 and the
tilt angle of the reception antenna 12 based on each of the
communication qualities of the uplink and the downlink with respect
to the base station device 10 and on each communication quality of
the uplink and the downlink with respect to the adjacent base
station device. At this time, the tilt angle control unit 15
controls at least either of the tilt angle of the transmission
antenna 11 and the tilt angle of the reception antenna 12, so that
a difference in a position of the cell boundary of the downlink
between the cell in which the base station device 10 and the
adjacent cell in which the adjacent base station device is arranged
and a position of the cell boundary of the uplink therebetween is
decreased.
For example, when the cell boundary of the downlink is farther than
the cell boundary of the uplink from the base station device 10,
the tilt angle control unit 15 increases the tilt angle of the
transmission antenna 11 to reduce the cell of the downlink.
Furthermore or instead, the tilt angle control unit 15 decreases
the tilt angle of the reception antenna 12 to enlarge the cell of
the uplink. Moreover, when the cell boundary of the uplink is
farther than the cell boundary of the downlink from the base
station device 10, the tilt angle control unit 15 increases the
tilt angle of the reception antenna 12 to reduce the cell of the
uplink. Furthermore or instead, the tilt angle control unit 15
increases the tilt angle of the transmission antenna 11 to enlarge
the cell of the downlink.
Based on each of the communication qualities of the uplink and the
downlink and on each communication quality of the uplink and the
downlink with respect to the base station device 10, determination
is made to determine whether the cell boundary of the uplink or the
cell boundary of the uplink is closer to the base station device
10.
For example, when the communication quality of each of the downlink
and the uplink is measured between the communication device near
the cell boundary and the base station device 10 and between the
communication device near the cell boundary and the adjacent base
station device, the measurement indicates whether the cell boundary
of the uplink or the cell boundary of the downlink is closer to the
base station device 10. That is, based on the difference of the
communication quality of the downlink between the base station
device 10 and the adjacent base station device and on the
difference of the communication quality of the uplink between the
base station device 10 and the adjacent base station device, the
determination may be made to determine whether the cell boundary of
the uplink or the cell boundary of the uplink is closer to the base
station device 10.
Therefore, for example, the tilt angle control unit 15 may control
the tilt angle of the transmission antenna 11, so that the
difference between the communication quality of the downlink
between the communication device positioned in a prescribed
position and the base station device 10 and the communication
quality of the downlink between the communication device and the
adjacent base station device may be decreased. For example, the
tilt angle control unit 15 may control the tilt angle of the
reception antenna, so that the difference between the communication
quality of the uplink between the communication device positioned
in the prescribed position and the base station device 10 and the
communication quality of the downlink between the communication
device and the adjacent base station device may be decreased.
Moreover, for example, as for a plurality of mobile stations, by
determining the base station device in which the highest
communication quality is measured on each of the uplink and the
downlink, determination may be made to determine whether the cell
boundary of the downlink or the cell boundary of the uplink is
closer to the base station device 10. At this time, the
determination is made to determine groups of the mobile stations.
The mobile station device belongs to Group A if the base station
device in which the highest communication quality of the downlink
is measured is the base station device 10. The mobile station
device belongs to Group B if the base station device in which the
highest communication quality of the uplink is measured is the base
station device 10.
If the number of the mobile stations belonging to Group A is larger
than the number of the mobile stations belonging to Group B, the
cell boundary of the uplink is closer than the cell boundary of the
downlink to the base station device 10. If the number of the mobile
stations belonging to Group B is larger than the number of the
mobile stations belonging to Group A, the cell boundary of the
downlink is closer than the cell boundary of the uplink to the base
station device 10. Therefore, for example, the tilt angle control
unit 15 may control at least either of the tilt angle of the
transmission antenna 11 and the tilt angle of the reception antenna
12, so that mismatch between the number of the mobile stations
belonging to Group A and Group B is reduced.
An example that the mobile station in which a handover occurs is
close to the cell boundary of the downlink may be used. That is, by
measuring the communication quality of the uplink between the
mobile station in which the handover occurs and the base station
device 10 and between the mobile station in which the handover
occurs and the adjacent base station device, respectively, the
determination may be made to determine whether the cell boundary of
the uplink or the cell boundary of the downlink is closer to the
base station device 10.
Therefore, for example, the tilt angle control unit 15 controls the
tilt angle to decrease the difference between the communication
quality of the uplink between the mobile station performing
handover processing and the base station device 10 and the
communication quality of the uplink between the mobile station and
the adjacent base station device.
According to the present embodiment, at least either of the tilt
angle of the transmission antenna 11 and the tilt angle of the
reception antenna 12 may be controlled, so that the difference
between the cell boundary of the downlink and the cell boundary of
the uplink between the adjacent cells is decreased.
It is assumed that the base station devices, which have different
transmission power, are arranged in two adjacent cells,
respectively. By the above-described control, the tilt angle of the
transmission antenna 11 in the base station device whose
transmission power is relatively large may be controlled to be
larger than the tilt angle of the reception antenna 12, for
example. If the tilt angle is controlled as described above, the
cell radius of the downlink of the cell in which the base station
device whose transmission power is relatively large is decreased,
and the cell radius of the uplink thereof is enlarged.
On the other hand, the tilt angle of the transmission antenna 11 in
the base station device whose transmission power is relatively
small may be controlled to be smaller than the tilt angle of the
reception antenna 12, for example. If the tilt angle is controlled
as described above, the cell radius of the downlink of the cell in
which the base station device whose transmission power is
relatively small is enlarged, and the cell radius of the uplink
thereof is decreased.
Next, description will be made of embodiments of a radio
communication system that includes a base station device. FIG. 3 is
a configuration diagram of a first embodiment of the radio
communication system. Reference numeral 10-1 indicates a base
station device. Reference numeral 10-2 indicates an adjacent base
station device. Reference Numeral 50 indicates a communication
device. Reference numeral 51 indicates a transmission antenna of
the communication device 50. Reference numeral 52 indicates a
reception antenna of the communication device 50.
A radio communication system 1 includes the base station device
10-1 and the adjacent base station device 10-2. According to the
present embodiment, the communication device 50 is arranged in a
desired cell boundary position that is previously prescribed as a
target position of the cell boundary of the downlink to adjust the
tilt angle of the transmission antenna 11 of the base station
device 10-1. For example, a middle position between the cell
boundary of the downlink and the cell boundary of the uplink before
the adjustment of the tilt angle of the transmission antenna 11
and/or the reception antenna 12 may be used as the above-described
target position.
Each of the base station device 10-1 and the adjacent base station
device 10-2 transmits, to the communication device 50, a downlink
reference signal for communication quality measurement in the
downlink. The communication device 50 measures the communication
quality of the downlink between the base station device 10-1 and
the communication device 50 and measures the communication quality
of the downlink between the adjacent base station device 10-2 and
the communication device 50 in the above-described desired target
position.
FIG. 4 is a diagram illustrating a first example of the
configuration of the base station device 10-1 illustrated in FIG.
3. The adjacent base station device 10-2 may have the similar
configuration as the base station device 10-1. This may be said to
the following other embodiments. Reference numeral 16 indicates a
downlink reference signal transmission unit. Reference numeral 17
indicates a downlink communication quality acquiring unit. The same
components as in FIG. 1 have the same reference numerals that are
used in FIG. 1.
The base station device 10-1 includes the transmission antenna 11,
the reception antenna 12, the tilt angle changing unit 13, the tilt
angle control unit 15, the downlink reference signal transmission
unit 16, and the downlink communication quality acquiring unit 17.
The downlink reference signal transmission unit 16 transmits the
downlink reference signal through the transmission antenna 11. The
downlink reference signal is used when the communication device 50
measures the communication quality of the downlink between the base
station device 10-1 and the communication device 50.
The downlink communication quality acquiring unit 17 receives
downlink communication quality information, which is transmitted
from the communication device 50 and indicates the communication
quality of the downlink between the base station device 10-1 and
the communication device 50. Moreover, the downlink communication
quality acquiring unit 17 may receive the downlink communication
quality information with respect to the downlink between the
adjacent base station device 10-2 and the communication device
50.
FIG. 5 is a diagram illustrating a configuration example of the
communication device 50 illustrated in FIG. 3. Reference numeral 53
indicates a downlink communication quality measuring unit.
Reference numeral 54 indicates a downlink communication quality
information transmission unit. The communication device 50 includes
the transmission antenna 51, the reception antenna 52, the downlink
communication quality measuring unit 53, and the downlink
communication quality information transmission unit 54.
The downlink communication quality measuring unit 53 measures the
communication quality of the downlink between the base station
device 10-1 and the communication device 50 and measures the
communication quality of the downlink between the adjacent base
station device 10-2 and the communication device 50. For example,
the downlink communication quality measuring unit 53 may measure
the reception power of the downlink reference signals, which are
transmitted from the base station device 10-1 and the adjacent base
station device 10-2, respectively, as the communication quality of
the downlink.
The downlink communication quality information transmission unit 54
transmits, to the base station device 10-1, the downlink
communication quality information indicating the communication
quality of the downlink measured between the base station device
10-1 and the communication device 50. The downlink communication
quality information transmission unit 54 may transmit, to the base
station device 10-1, the downlink communication quality information
indicating the communication quality of the downlink measured
between the adjacent base station device 10-2 and the communication
device 50.
FIG. 6 is a diagram illustrating a configuration example of the
tilt angle control unit 15 illustrated in FIG. 4. Reference numeral
30 indicates a subtracter. Reference numeral 31 indicates a
comparison unit. Reference numeral 32 indicates an adjustment
amount deciding unit. The tilt angle control unit 15 includes the
subtracter 30, the comparison unit 31, and the adjustment amount
deciding unit 32.
The subtracter 30 inputs the downlink communication quality
information indicating the measured communication quality of the
downlinks between the base station device 10-1 and the
communication device 50 and between the adjacent base station
device 10-2 and the communication device 50, respectively. The
subtracter 30 calculates the difference of the communication
quality of the downlinks measured between the base station device
10-1 and the communication device 50 and between the adjacent base
station device 10-2 and the communication device 50,
respectively.
The comparison unit 31 compares the difference of the communication
quality to a prescribed threshold value T1. If the difference of
the communication quality is larger than the prescribed threshold
value T1, the adjustment amount deciding unit 32 decides an
adjustment amount to adjust the tilt angle of the transmission
antenna 11. For example, if the communication quality between the
base station device 10-1 and the communication device 50 is higher
than the communication quality between the adjacent base station
device 10-2 and the communication device 50, the adjustment amount
deciding unit 32 decides the adjacent amount to increase the tilt
angle of the transmission antenna 11. On the other hand, if the
communication quality between the adjacent base station device 10-2
and the communication device 50 is higher than the communication
quality between the base station device 10-1 and the communication
device 50, the adjustment amount deciding unit 32 decides the
adjustment amount to decrease the tilt angle of the transmission
antenna 11.
The adjustment amount deciding unit 32 may decide the adjustment
amount based on, for example, a table and a calculating formula
that previously determine a relation between the difference of the
communication quality and the adjustment amount of the tilt angle.
Moreover, for example, the adjustment amount decided in one
adjustment by the adjustment amount deciding unit 32 may be the
adjustment amount of a fixed step angle .DELTA..theta..
The tilt angle changing unit 13 illustrated in FIG. 4 mechanically
or electrically changes the tilt angle of the transmission antenna
11 based on the adjustment amount decided by the adjustment amount
deciding unit 32.
FIG. 7 is an explanation diagram of a control example of the tilt
angle of the transmission antenna in the radio communication system
illustrated in FIG. 3. In Operation BA, an operator, who adjusts
the tilt angle of the transmission antenna 11, arranges the
communication device 50 in the desired cell boundary position.
In Operation BB, the downlink reference signal transmission unit 16
of the base station device 10-1 and of the adjacent base station
device 10-2 transmits the downlink reference signal, respectively.
In Operation BC, the downlink communication quality measuring unit
53 of the communication device 50 measures the communication
quality of the downlink between the base station device 10-1 and
the communication device 50 and measures the communication quality
of the downlink between the adjacent base station device 10-2 and
the communication device 50.
In Operation BD, the downlink communication quality information
transmission unit 54 transmits, to the base station device 10-1,
the downlink communication quality information with respect to each
of the downlinks between the base station device 10-1 and the
communication device 50 and between the adjacent base station
device 10-2 and the communication device 50.
In Operation BE, the tilt angle control unit 15 of the base station
device 10-1 determines whether or not if the difference of the
communication quality of each of the downlinks between the base
station device 10-1 and the communication device 50 and between the
adjacent base station device 10-2 and the communication device 50
is smaller than or equal to the threshold value T1. If the
difference of the communication quality is smaller than or equal to
the threshold value T1 (Y in Operation BE), the processing ends. If
the difference of the communication quality is not smaller than or
equal to the threshold value T1 (N in Operation BE), the process
goes to Operation BF.
In Operation BF, the tilt angle control unit 15 determines whether
or not if the communication quality between the base station device
10-1 and the communication device 50 is higher than the
communication quality between the adjacent base station device 10-2
and the communication device 50. The communication quality between
the base station device 10-1 and the communication device 50 is
higher than the communication quality between the adjacent base
station device 10-2 and the communication device 50 (Y in Operation
BF), the process goes to Operation BG. If the communication quality
between the base station device 10-1 and the communication device
50 is not higher than the communication quality between the
adjacent base station device 10-2 and the communication device 50
(N in Operation BF), the process goes to Operation BH.
In Operation BG, the adjustment amount deciding unit 32 decides the
adjustment amount to increase the tilt angle of the transmission
antenna 11. In Operation BH, the adjustment amount deciding unit 32
decides the adjustment amount to decrease the tilt angle of the
transmission antenna 11. The tilt angle changing unit 13 changes
the tilt angle of the transmission antenna 11 based on the decided
adjustment amount. After Operation BG or Operation BH, the process
goes back to Operation BB. Operations BB to BH are repeated until
the difference of the communication quality reaches or becomes
smaller than the threshold value T1 in the determination in
Operation BE.
According to the present embodiment, the tilt angle of the
transmission antenna 11 may be adjusted in that the cell boundary
of the downlink is positioned closer to the desired target
position. Therefore, according to the present embodiment, the
position of the cell boundary of the downlink may be controlled
when the difference between the cell boundary of the downlink and
the cell boundary of the uplink between the adjacent cells may be
eliminated or decreased.
FIG. 8 is a diagram illustrating a second example of the
configuration of the base station device 10-1 illustrated in FIG.
3. Reference numeral 18 indicates an inter-base station
communication unit. Reference numeral 19 indicates an adjacent cell
communication quality acquiring unit. The same components as in
FIG. 4 have the same reference numerals that are used in FIG. 4.
The base station device 10-1 includes the transmission antenna 11,
the reception antenna 12, the tilt angle changing unit 13, the tilt
angle control unit 15, the downlink reference signal transmission
unit 16, the downlink communication quality acquiring unit 17, and
the inter-base station communication unit 18. The inter-base
station communication unit 18 includes the adjacent cell
communication quality acquiring unit 19.
In the embodiments described with reference to FIG. 3 to FIG. 7,
the communication device 50 transmits, to the base station device
10-1, the downlink communication quality information with respect
to both the downlinks between the base station device 10-1 and the
communication device 50 and between the adjacent base station
device 10-2 and the communication device 50.
Instead, the communication device 50 according to the present
embodiment transmits, to the base station device 10-1, the downlink
communication quality information between the base station device
10-1 and the communication device 50, and transmits, to the
adjacent base station device 10-2, the downlink communication
quality information between the adjacent base station device 10-2
and the communication device 50. The adjacent base station device
10-2 transmits the transmitted downlink communication quality
information to the base station device 10-1 by the inter-base
station communication unit 18. The adjacent cell communication
quality acquiring unit 19 of the base station device 10-1 acquires
the downlink communication quality information, transmitted from
the adjacent base station device 10-2, between the adjacent base
station device 10-2 and the communication device 50.
According to the present embodiment, the base station device 10-1
may acquire the downlink communication quality information with
respect to both the downlinks between the base station device 10-1
and the communication device 50 and between the adjacent base
station device 10-2 and the communication device 50.
Next, description will be made of other embodiments of the radio
communication system. FIG. 9 is a configuration diagram of a second
embodiment of the radio communication system. In the present
embodiment, the communication device 50 is arranged in the desired
cell boundary position, which is previously specified as the
desired target position of the cell boundary of the downlink, to
adjust the tilt angle of the transmission antenna 11 of the base
station device 10-1.
The communication device 50 transmits, from the above-described
desired target position, the uplink reference signal for the
communication quality measurement in the uplink. The base station
device 10-1 measures the communication quality of the uplink
between the base station device 10-1 and the communication device
50 by receiving the uplink reference signal transmitted from the
communication device 50. In the same manner, the adjacent base
station device 10-2 measures the communication quality of the
uplink between the adjacent base station device 10-2 and the
communication device 50.
The base station device 10-1 according to the present embodiment
may include the configuration illustrated in FIG. 4 to adjust the
tilt angle of the transmission antenna 11. In the same manner, the
communication device 50 according to the present embodiment may
include the configuration illustrated in FIG. 5 to adjust the tilt
angle of the transmission antenna 11 of the base station device
10-1.
FIG. 10 is a diagram illustrating a configuration example of the
communication device 50 illustrated in FIG. 9. Reference numeral 55
indicates an uplink reference signal transmission unit. The same
components as in FIG. 5 have the same reference numerals that are
used in FIG. 5. The communication device 50 includes the
transmission antenna 51, the reception antenna 52, and the uplink
reference signal transmission unit 55. The uplink reference signal
transmission unit 55 transmits the uplink reference signal through
the transmission antenna 51. The uplink reference signal is used
when the base station device 10-1 measures the communication
quality of the uplink between the base station device 10-1 and the
communication device 50.
FIG. 11 is a diagram illustrating a configuration example of the
base station device 10-1 illustrated in FIG. 9. Reference numeral
20 indicates an uplink communication quality measuring unit. The
same components as in FIG. 1 or FIG. 8 have the same reference
numerals that are used in FIG. 1 or FIG. 8. The base station device
10-1 includes the transmission antenna 11, the reception antenna
12, the tilt angle changing unit 14, the tilt angle control unit
15, the inter-base station communication unit 18, and the uplink
communication quality measuring unit 20. The inter-base station
communication unit 18 includes the adjacent cell communication
quality acquiring unit 19.
The uplink communication quality measuring unit 20 measures the
communication quality of the uplink between the base station device
10-1 and the communication device 50. For example, the uplink
communication quality measuring unit 20 may measure the reception
power of the uplink reference signal, which is transmitted from the
communication device 50, as the communication quality of the
uplink.
The inter-base station communication unit 18 transmits, to the
adjacent base station device 10-2, uplink communication quality
information with respect to the uplink measured by the uplink
communication quality measuring unit 20. The adjacent cell
communication quality acquiring unit 19 receives the uplink
communication quality information, which is measured in the same
way as in the adjacent base station device 10-2, with respect to
the uplink between the adjacent base station device 10-2 and the
communication device 50.
The tilt angle control unit 15 decides the adjustment amount of the
tilt angle of the reception antenna 12 to decrease the difference
between the communication quality of the uplink between the
communication device 50 and the base station device 10-1 and the
communication quality of the uplink between the communication
device 50 and the adjacent base station device 10-2. The tilt angle
changing unit 14 mechanically or electrically changes the tilt
angle of the reception antenna 12 based on the adjustment amount
decided by the tilt angle control unit 15. The configuration of the
tilt angle control unit 15 may be substantially the same as the
configuration described above with reference to FIG. 6.
FIG. 12 is an explanation diagram of a control example of a tilt
angle of a reception antenna in the radio communication system
illustrated in FIG. 9. In Operation CA, an operator, who adjusts
the tilt angle of the reception antenna 12, arranges the
communication device 50 in the desired cell boundary position.
In Operation CB, the uplink reference signal transmission unit 55
of the communication device 50 transmits the uplink reference
signal. In Operation CC, each of the uplink communication quality
measuring units 20 of the base station device 10-1 and of the
adjacent base station device 10-2 measures the communication
quality between the base station device 10-1 and the communication
device 50 and between the adjacent base station device 10-2 and the
communication device 50.
In Operation CD, the inter-base station communication unit 18
transmits the uplink communication quality information to the
adjacent base station device 10-2. The adjacent cell communication
quality acquiring unit 19 receives the uplink communication quality
information, which is measured by the adjacent base station device
10-2, with respect to the uplink between the adjacent base station
device 10-2 and the communication device 50.
In Operation CE, the tilt angle control unit 15 of the base station
device 10-1 determines whether or not if the difference of the
communication quality of the uplinks between the base station
device 10-1 and the communication device 50 and between the
adjacent base station device 10-2 and the communication device 50
is smaller than or equal to a threshold value T2. If the difference
of the communication quality is smaller than or equal to the
threshold value T2 (Y in Operation CE), the processing ends. If the
difference of the communication quality is not smaller than or
equal to the threshold value T2 (N in Operation CE), the process
goes to Operation CF.
In Operation CF, the tilt angle control unit 15 determines whether
or not if the communication quality between the base station device
10-1 and the communication device 50 is higher than the
communication quality between the adjacent base station device 10-2
and the communication device 50. If the communication quality
between the base station device 10-1 and the communication device
50 is higher than the communication quality between the adjacent
base station device 10-2 and the communication device 50 (Y in
Operation CF), the process goes to Operation CG. If the
communication quality between the base station device 10-1 and the
communication device 50 is not higher than the communication
quality between the adjacent base station device 10-2 and the
communication device 50 (N in Operation CF), the process goes to
Operation CH.
In Operation CG, the adjustment amount deciding unit 32 decides the
adjustment amount to increase the tilt angle of the reception
antenna 12. In Operation CH, the adjustment amount deciding unit 32
decides the adjustment amount to decrease the tilt angle of the
reception antenna 12. The tilt angle changing unit 14 changes the
tilt angle of the reception antenna 12 based on the decided
adjustment amount. After Operation CG or Operation CH, the process
goes back to Operation CB. Operations CB to CH are repeated until
the difference of the communication quality reaches or becomes
smaller than the threshold value T2 in the determination in
Operation CE.
According to the present embodiment, the tilt angle of the
reception antenna 12 may be adjusted in that the cell boundary of
the uplink is positioned in the desired target position. Therefore,
according to the present embodiment, the position of the cell
boundary of the uplink may be controlled when the difference of the
cell boundary of the uplink and the cell boundary of the downlink
between the adjacent cells may be eliminated or decreased.
Next, description will be made of other embodiments for adjusting
the tilt angle of the reception antenna 12 of the base station
device 10-1 by using the communication device 50 positioned in the
above-described desired target position. Description will be made
of other embodiments of the radio communication system. FIG. 13 is
a configuration diagram of a third embodiment of the radio
communication system. The base station device 10-1 according to the
present embodiment may include the configuration illustrated in
FIG. 4 to adjust the tilt angle of the transmission antenna 11.
Similarly, the communication device 50 according to the present
embodiment may include the configuration illustrated in FIG. 5 to
adjust the tilt angle of the transmission antenna 11 of the base
station device 10-1.
In the present embodiment, the base station device 10-1 and the
adjacent base station device 10-2 transmit, from each of the
reception antennas 12 thereof, the uplink reference signal for
communication quality measurement in the uplink. The communication
device 50 measures the communication quality of each of the uplinks
between the base station device 10-1 and the communication device
50 and between the adjacent base station device 10-2 and the
communication device 50 by receiving each of the uplink reference
signals from the base station device 10-1 and the adjacent base
station device 10-2 in the above-described desired target
position.
FIG. 14 is a diagram illustrating a configuration example of the
base station device 10-1 illustrated in FIG. 13. Reference numeral
21 indicates an uplink reference signal transmission unit.
Reference numeral 22 indicates an uplink communication quality
acquiring unit. The same components as in FIG. 11 have the same
reference numerals that are used in FIG. 11. The base station
device 10-1 includes the transmission antenna 11, the reception
antenna 12, the tilt angle changing unit 14, the tilt angle control
unit 15, the uplink reference signal transmission unit 21, and the
uplink communication quality acquiring unit 22.
The uplink reference signal transmission unit 21 transmits the
uplink reference signal through the reception antenna 12. As
described below, the uplink reference signal is used when the
communication device 50 measures the communication quality of the
uplink between the base station device 10-1 and the communication
device 50. When the downlink reference signal is transmitted from
the transmission antenna 11 of the base station device 10-1
separately, the uplink reference signal may be transmitted in a
time slot or a time frame that is different from the time slot or
the time frame of the downlink reference signal or may be a signal
orthogonal in frequency or code.
The uplink communication quality acquiring unit 22 receives the
uplink communication quality information, which is transmitted from
the communication device 50 and indicates the communication quality
of the uplink between the base station device 10-1 and the
communication device 50. Moreover, the uplink communication quality
acquiring unit 22 receives the uplink communication quality
information with respect to the uplink between the adjacent base
station device 10-2 and the communication device 50.
FIG. 15 is a diagram illustrating a configuration example of the
communication device 50 illustrated in FIG. 13. Reference numeral
56 indicates an uplink communication quality measuring unit.
Reference numeral 57 indicates an uplink communication quality
information transmission unit. The same components as in FIG. 5
have the same reference numerals that are used in FIG. 5. The
communication device 50 includes the transmission antenna 51, the
reception antenna 52, the uplink communication quality measuring
unit 56, and the uplink communication quality information
transmission unit 57.
The uplink communication quality measuring unit 56 measures the
communication quality of the uplink between the base station device
10-1 and the communication device 50 and measures the communication
quality of the uplink between the adjacent base station device 10-2
and the communication device 50. For example, the uplink
communication quality measuring unit 56 calculates transmission
loss by subtracting the reception power of the uplink reference
signal, which is received from each of the base station device 10-1
and the adjacent base station device 10-2, from the previously
reported transmission power of each of the base station device 10-1
and the adjacent base station device 10-2. The uplink communication
quality measuring unit 56 may measure the communication quality of
each of the downlinks based on each of the transmission loss.
The uplink communication quality information transmission unit 57
transmits, to the base station device 10-1, the uplink
communication quality information between the base station device
10-1 and the communication device 50. The uplink communication
quality information transmission unit 57 may transmit, to the base
station device 10-1, the uplink communication quality information
between the adjacent base station device 10-2 and the communication
device 50.
FIG. 16 is an explanation diagram of a control example of a tilt
angle of a reception antenna in the radio communication system
illustrated in FIG. 13. In Operation DA, the operator, who adjusts
the tilt angle of the reception antenna 12, arranges the
communication device 50 in the desired cell boundary position.
In Operation DB, each of the uplink reference signal transmission
units 21 of the base station device 10-1 and of the adjacent base
station device 10-2 transmits the uplink reference signal. In
Operation DC, the uplink communication quality measuring unit 56 of
the communication device 50 measures the communication quality of
the uplink between the base station device 10-1 and the
communication device 50 and measures the communication quality of
the uplink between the adjacent base station device 10-2 and the
communication device 50.
In Operation DD, the downlink communication quality information
transmission unit 54 transmits, to the base station device 10-1,
the uplink communication quality information with respect to each
of the uplinks between the base station device 10-1 and the
communication device 50 and between the adjacent base station
device 10-2 and the communication device 50.
In Operation DE, the tilt angle control unit 15 of the base station
device 10-1 determines whether or not if the difference of the
communication quality of the uplinks between the base station
device 10-1 and the communication device 50 and between the
adjacent base station device 10-2 and the communication device 50
is smaller than or equal to the threshold value T2. If the
difference of the communication quality is smaller than or equal to
the threshold value T2 (Y in Operation DE), the processing ends. If
the difference of the communication quality is not smaller than or
equal to the threshold value T2 (N in Operation DE), the process
goes to Operation DF.
In Operation DF, the tilt angle control unit 15 determines whether
or not the communication quality between the base station device
10-1 and the communication device 50 is higher than the
communication quality between the adjacent base station device 10-2
and the communication device 50. If the communication quality
between the base station device 10-1 and the communication device
50 is higher than the communication quality between the adjacent
base station device 10-2 and the communication device 50 (Y in
Operation DF), the process goes to Operation DG. If the
communication quality between the base station device 10-1 and the
communication device 50 is not higher than the communication
quality between the adjacent base station device 10-2 and the
communication device 50 (N in Operation DF), the process goes to
Operation DH.
In Operation DG, the adjacent amount deciding unit 32 decides the
adjustment amount to increase the tilt angle of the reception
antenna 12. In Operation DH, the adjustment amount deciding unit 32
decides the adjustment amount to decrease the tilt angle of the
reception antenna 12. The tilt angle changing unit 14 changes the
tilt angle of the reception antenna 12 based on the decided
adjustment amount. After Operation DG or Operation DH, the process
goes back to Operation DB. Operations DB to DH are repeated until
the difference of the communication quality reaches or becomes
smaller than the threshold value T2 in the determination in
Operation DE.
According to the present embodiment, the base station device 10-1
may acquire the uplink communication quality information between
the base station device 10-1 and the adjacent base station device
10-2 and may adjust the tilt angle of the reception antenna 12.
In the embodiments described with reference to FIG. 13 to FIG. 16,
the communication device 50 transmits, to the base station device
10-1, the uplink communication quality information with respect to
both the uplinks between the base station device 10-1 and the
communication device 50 and between the adjacent base station
device 10-2 and the communication device 50. Instead, the
communication device 50 may transmit the uplink communication
quality information between the base station device 10-1 and the
communication device 50 to the base station device 10-1 and may
transmit the uplink communication quality information between the
adjacent base station device 10-2 and the communication device 50
to the adjacent base station device 10-2. As with the embodiments
described with reference to FIG. 8, the base station device 10-1
may acquire the downlink communication quality information between
the adjacent base station device 10-2 and the communication device
50 through inter-base station communication between the base
station device 10-1 and the adjacent base station device 10-2.
Next, description will be made of other embodiments of the radio
communication system. FIG. 17 is a configuration diagram of a
fourth embodiment of the radio communication system. Each of
reference numerals 60-1 and 60-2 to 60-n is a mobile station that
performs communication with the base station device 10-1 or the
adjacent base station device 10-2. The mobile stations 60-1 and
60-2 to 60-n may be collectively referred to as a mobile station
60. Reference numeral 61 indicates a transmission antenna of the
mobile station 60. Reference numeral 62 indicates a reception
antenna of the mobile station 60. A radio communication system 1
includes the base station device 10-1, the adjacent base station
device 10-2, and the mobile stations 60-1 and 60-2 to 60-n.
Each of the base station device 10-1 and the adjacent base station
device 10-2 transmits the downlink reference signal to the mobile
station 60. Based on the reception quality of the received downlink
reference signal, the mobile station 60 determines the cell in
which the base station device whose reception quality of the
downlink is the highest is arranged as a downlink communication
cell. The mobile station 60 transmits downlink communication cell
information, which indicates the determined downlink communication
cell, to the base station device 10-1 that is arranged in the
determined downlink communication cell.
The mobile station 60 transmits the uplink reference signal. By
receiving the uplink reference signal transmitted from the mobile
station 60, the base station device 10-1 measures the communication
quality of the uplink between the base station device 10-1 and the
mobile station 60. In substantially the same manner, the adjacent
base station device 10-2 measures the communication quality of the
uplink between the adjacent base station device 10-2 and the mobile
station 60.
FIG. 18 is a diagram illustrating a configuration example of the
mobile station 60 illustrated in FIG. 17. Reference numeral 63
indicates a downlink communication quality measuring unit.
Reference numeral 64 indicates a downlink communication cell
deciding unit. Reference numeral 65 indicates an uplink reference
signal transmission unit. The mobile station 60 includes the
transmission antenna 61, the reception antenna 62, the downlink
communication quality measuring unit 63, the downlink communication
cell deciding unit 64, and the uplink reference signal transmission
unit 65.
Based on the downlink reference signal received from each of the
base station device 10-1 and other base station devices including
the adjacent base station device 10-2, the downlink communication
quality measuring unit 63 measures the reception quality of each of
the downlinks between each of the base station devices and the
mobile station 60. For example, the downlink communication quality
measuring unit 63 may measure the reception power of the reference
signal, which is transmitted from each of the base station devices,
as the reception quality of each of the downlinks thereof.
Based on the reception quality of the downlink, the downlink
communication cell deciding unit 64 decides the cell in which the
base station device whose reception quality of the downlink is the
highest is arranged as a downlink communication cell. The downlink
communication cell deciding unit 64 transmits the downlink
communication cell information, which indicates the decided
downlink communication cell, to the base station device that is
arranged in the decided downlink communication cell. The downlink
communication cell information may include, for example, an
identifier of the mobile station 60 and the identifier of the
downlink communication cell.
The uplink reference signal transmission unit 65 transmits the
uplink reference signal through the transmission antenna 61. The
uplink reference signal is used when the base station device 10-1
and the other base station devices including the adjacent base
station device 10-2 measure the communication quality of the uplink
between each of the base station devices and the mobile station 60.
The uplink reference signal is transmitted in a form in association
with identifier information of the mobile station 60 transmitted
from the mobile station 60. For example, the uplink reference
signal may include the identifier of the mobile station 60 or may
indicate the identifier of the mobile station 60. Moreover, for
example, the uplink reference signal may be associated with the
identifier of the mobile station 60 by being transmitted, from the
mobile station 60, in substantially the same time slot or
substantially the same data frame as of the identifier of the
mobile station 60.
FIG. 19 is a diagram illustrating a configuration example of the
base station device 10-1 illustrated in FIG. 17. Reference numeral
23 indicates a connection cell instruction information acquiring
unit. Reference numeral 24 indicates an adjacent cell connection
information acquiring unit. The same components as in FIG. 4 or
FIG. 11 have the same reference numerals that are used in FIG. 4 or
FIG. 11. The base station device 10-1 includes the transmission
antenna 11, the reception antenna 12, the tilt angle changing units
13 and 14, the tilt angle control unit 15, the downlink reference
signal transmission unit 16, the inter-base station communication
unit 18, the uplink communication quality measuring unit 20, and
the connection cell instruction information acquiring unit 23. The
inter-base station communication unit 18 includes the adjacent cell
communication quality acquiring unit 19 and the adjacent cell
connection information acquiring unit 24.
The downlink reference signal transmission unit 16 transmits the
downlink reference signal through the transmission antenna 11. The
downlink reference signal is used when the mobile station 60
measures the reception quality of the downlink between the base
station device 10-1 and the mobile station 60. The connection cell
instruction information acquiring unit 23 receives, through the
reception antenna 12, the downlink communication cell instruction
information that is transmitted from the mobile station 60.
The inter-base station communication unit 18 transmits, to the
adjacent base station device 10-2, the downlink communication cell
instruction information acquired by the connection cell instruction
information acquiring unit 23.
The adjacent cell connection information acquiring unit 24 receives
the downlink connection instruction information that is acquired by
the connection cell instruction information acquiring unit 23 of
the adjacent base station device 10-2 and is then transmitted from
the adjacent base station device 10-2. The downlink communication
cell instruction information acquired by the connection cell
instruction information acquiring unit 23 and the downlink
communication cell indication information acquired by the adjacent
cell connection information acquiring unit 24 are output to the
tilt angle control unit 15.
The uplink communication quality measuring unit 20 measures the
communication quality of the uplink between the base station device
10-1 and the mobile station 60. For example, the uplink
communication quality measuring unit 20 may measure the reception
power of the uplink reference signal, which is transmitted from the
mobile station 60, as the communication quality of the uplink. The
uplink communication quality measuring unit 20 generates uplink
communication quality information indicating the measured
communication quality of the uplink. The uplink communication
quality information may include the communication quality of the
uplink, the identifier of the cell in which the base station device
10-1 is arranged, and the identifier of the mobile station 60.
The inter-base station communication unit 18 transmits, to the
adjacent base station device 10-2, the uplink communication quality
information generated by the uplink communication quality measuring
unit 20.
The adjacent cell communication quality acquiring unit 19 receives
the uplink communication quality information that is generated by
the uplink communication quality measuring unit 20 of the adjacent
base station device 10-2 and is then transmitted from the adjacent
base station device 10-2. The uplink communication quality
information generated by the uplink communication quality measuring
unit 20 and the uplink communication quality information acquired
by the adjacent cell communication quality acquiring unit 19 are
output to the tilt angle control unit 15.
FIG. 20 is a diagram illustrating a configuration example of the
tilt angle control unit 15 illustrated in FIG. 19. Reference
numeral 32 indicates an adjustment amount deciding unit. Reference
numeral 33 indicates a correspondence relation information
generation unit. Reference numeral 34 indicates a correspondence
relation information storage unit. Reference numeral 35 indicates
an asymmetric degree deciding unit. The correspondence relation
information generation unit 33 generates a correspondence relation
information 36 based on the downlink communication cell information
and the downlink communication quality information that are input
to the tilt angle control unit 15. The correspondence relation
information 36 is stored in the correspondence relation information
storage unit 34.
The correspondence relation information 36 indicates a
correspondence relation between each mobile station 60 and the cell
decided as a downlink communication cell in the mobile station 60.
In this case, the downlink communication cell is a cell in which
the base station device whose reception quality of the downlink
reference signal is the highest is located.
Therefore, the correspondence relation information 36 indicates a
correspondence relation between each mobile station 60 and the base
station device whose communication quality of the downlink between
each mobile station 60 and the cell in which the base station
device is located is measured to be the highest with respect to the
mobile station 60. Furthermore, the correspondence relation
information 36 indicates the correspondence relation between each
mobile station 60 and the cell in which the base station device
whose communication quality of the uplink between each mobile
station 60 and the cell in which the base station device is located
is measured to be the highest.
FIG. 21 is an explanation diagram of a realization example of the
correspondence relation information 36. The correspondence relation
information 36 may be realized by, for example, a table structure
illustrated in FIG. 21. The table illustrated in FIG. 21 has a
column for storing the identifier of each mobile station 60, a
column for storing the identifier of the downlink communication
cell of the mobile station 60, and a column for storing the
identifier of the cell of the base station device whose
communication quality of the downlink between the mobile station 60
and the cell in which the base station device is measured to be the
highest. For convenience of the description, the cell of the base
station device whose communication quality of the uplink between
the mobile station 60 and the cell thereof is measured to be the
highest may be referred to as an "uplink highest quality cell."
If the uplink-and-downlink asymmetric state does not occur, the
downlink communication cell of each mobile station 60 almost
corresponds to the uplink highest quality cell. Accordingly, if the
uplink-and-downlink asymmetric state does not occur, the number of
the mobile stations 60 where the arrangement cell of the base
station device 10-1 is the downlink communication cell is
substantially the same as the number of the mobile stations 60
where the arrangement cell of the base station device 10-1 is the
uplink highest quality cell.
The asymmetric degree deciding unit 35 illustrated in FIG. 20
calculates a difference, as an "asymmetric degree," between the
number of the mobile stations 60 where the arrangement cell of the
base station device 10-1 is the downlink communication cell and the
number of the mobile stations 60 where the arrangement cell of the
base station device 10-1 is the uplink highest quality cell. For
example, the asymmetric degree deciding unit 35 may calculate the
difference, as an asymmetric degree, between the number of the
mobile stations 60 where the arrangement cell of the base station
device 10-1 is the downlink communication cell and the number of
the mobile stations 60 where the arrangement cell of the base
station device 10-1 is the uplink highest quality cell.
Furthermore, for example, the asymmetric degree deciding unit 35
may calculate a ratio, as an asymmetric degree, of the number of
the mobile stations 60 where the arrangement cell of the base
station device 10-1 is the downlink communication cell to the
number of the mobile stations 60 where the arrangement cell of the
base station device 10-1 is the downlink highest quality cell.
If the asymmetric degree is larger than a prescribed threshold
value T3, the adjustment amount deciding unit 32 decides the
adjustment amount to adjust at least either of the tilt angle of
the transmission antenna 11 and the tilt angle of the reception
antenna 12. If the number of the mobile stations where the
arrangement cell of the base station device 10-1 is the downlink
communication cell is larger than the number of the mobile stations
where the arrangement cell of the base station device 10-1 is the
uplink highest quality cell, the adjustment amount deciding unit 32
decides the adjustment amount to increase the tilt angle of the
transmission antenna 11. Furthermore or instead, the adjustment
amount deciding unit 32 decides the adjustment amount to decrease
the tilt angle of the reception antenna 12.
If the number of the mobile stations where the arrangement cell of
the base station device 10-1 is the downlink communication cell is
smaller than the number of the mobile stations where the
arrangement cell of the base station device 10-1 is the uplink
highest quality cell, the adjustment amount deciding unit 32
decides the adjustment amount to decrease the tilt angle of the
transmission antenna 11. Furthermore or instead, the adjustment
amount deciding unit 32 decides the adjustment amount to increase
the tilt angle of the reception antenna 12. The adjustment amount
deciding unit 32 may decide the adjustment amount based on, for
example, the table and calculation formula that are used to
previously determine the relation between the asymmetric degree and
the adjustment amount of the tilt angle. Furthermore, for example,
the adjustment amount decided by the adjustment amount deciding
unit 32 in one adjustment may be the adjustment amount of the fixed
step angle .DELTA..theta..
FIG. 22 is an explanation diagram of a control example of the tilt
angle of the antenna in the radio communication system illustrated
in FIG. 17.
In Operation EA, the downlink reference signal transmission unit 16
of the base station device 10-1 and the other base station devices
including the adjacent base station device 10-2 transmits the
downlink reference signal. In Operation EB, the downlink
communication quality measuring unit 63 of the mobile station 60
measures the reception quality of each of the downlinks between
each of the base station devices and the mobile station 60. The
downlink communication cell deciding unit 64 decides the downlink
communication cell and transmits the downlink communication cell
information to the base station device arranged in the downlink
communication cell.
In Operation EC, the uplink reference signal transmission unit 65
of the mobile station 60 transmits the uplink reference signal. In
Operation ED, the uplink communication quality measuring unit 20 of
the base station device 10-1 and the other base stations including
the adjacent base station device 10-2 measures the communication
quality of each of the uplinks between each of the base station
devices and the mobile station 60.
In Operation EE, the inter-base station communication unit 18 of
the base station device 10-1 transmits, to the adjacent base
station device 10-2, the uplink communication quality information
generated by the uplink communication quality measuring unit 20.
The inter-base station communication unit 18 of the base station
device 10-1 transmits, to the adjacent base station device 10-2,
the downlink communication cell instruction information acquired by
the connection cell instruction information acquiring unit 23.
On the other hand, the adjacent cell communication quality
acquiring unit 19 of the base station device 10-1 receives the
uplink communication quality information transmitted from the
adjacent base station device 10-2. The adjacent cell connection
information acquiring unit 24 of the base station device 10-1
receives the downlink communication cell instruction information
transmitted from the adjacent base station device 10-2. In
Operation EF, the correspondence relation information generation
unit 33 of the base station device 10-1 generates the
correspondence relation information 36.
In Operation EG, the asymmetric degree deciding unit 35 of the base
station device 10-1 calculates the above-described asymmetric
degree. That is, the asymmetric degree deciding unit 35 calculates
the difference between the number of the mobile stations 60 where
the arrangement cell of the base station device 10-1 is the
downlink communication cell and the number of the mobile stations
60 where the arrangement cell of the base station device 10-1 is
the uplink highest quality cell. The adjustment amount deciding
unit 32 determines whether the asymmetric degree is smaller than or
equal to the prescribed threshold value T3. If the asymmetric
degree is smaller than or equal to the threshold value T3 (Y in
Operation EG), the processing ends. If the asymmetric degree is not
smaller than or equal to the threshold value T3 (N in Operation
EG), the process goes to Operation EH.
In Operation EH, the adjustment amount deciding unit 32 determines
whether the number of the mobile stations 60 where the arrangement
cell of the base station device 10-1 is the uplink highest quality
cell is larger or smaller than the number of the mobile stations 60
where the arrangement cell of the base station device 10-1 is the
downlink communication cell. If the number of the mobile stations
60 where the arrangement cell of the base station device 10-1 is
the uplink highest quality cell is larger than the number of the
mobile stations 60 where the arrangement cell of the base station
device 10-1 is the downlink communication cell (Y in Operation EH),
the process goes to Operation EI. If the number of the mobile
stations 60 where the arrangement cell of the base station device
10-1 is the uplink highest quality cell is not larger than the
number of the mobile stations 60 where the arrangement cell of the
base station device 10-1 is the downlink communication cell (N in
Operation EH), the process goes to Operation EJ.
In Operation EI, the adjustment amount deciding unit 32 decides the
adjustment amount to decrease the tilt angle of the transmission
antenna 11. Furthermore or instead, the adjustment amount deciding
unit 32 decides the adjustment amount to increase the tilt angle of
the reception antenna 12. In Operation EJ, the adjustment amount
deciding unit 32 decides the adjustment amount to increase the tilt
angle of the transmission antenna 11. Furthermore or instead, the
adjustment amount deciding unit 32 decides the adjustment amount to
decrease the tilt angle of the reception antenna 12. The tilt angle
changing unit 13 changes the tilt angle of the transmission antenna
11 based on the decided adjustment amount. Furthermore or instead,
the tilt angle changing unit 14 changes the tilt angle of the
reception antenna 12 based on the decided adjustment amount. After
Operation EI or Operation EJ, the process goes back to Operation
EB. Operations EB to EJ are repeated until the asymmetric degree
reaches or becomes smaller than the threshold value T3 in the
determination in Operation EG.
According to the present embodiment, the base station device 10-1
may control the tilt angle of the transmission antenna 11 and the
reception antenna 12 based on the downlink communication cell
instruction information transmitted from the mobile station 60 and
on the measured communication quality of the uplink between the
base station device 10-1 and the mobile station 60.
In the embodiments described with reference to FIG. 17 to FIG. 22,
each of the mobile stations 60 transmits the downlink communication
cell instruction information to the base station device that is
arranged in the downlink communication cell. Each of the base
station devices transmits the transmitted downlink communication
cell instruction information to the adjacent base station device by
the inter-base station communication unit 18. Instead, each of the
mobile stations 60 may transmit the downlink communication cell
instruction information to each of the base station devices
arranged in the downlink communication cell and the surrounding
cells. In this case, since the base station device 10-1 may
directly receive, from the mobile station 60, link connection cell
instruction information indicating the cell of the adjacent base
station device 10-2 as a downlink communication cell, the adjacent
cell connection information acquiring unit 24 may be omitted.
As with the embodiments described with reference to FIG. 13 to FIG.
16, in the embodiments described with reference to FIG. 17 to FIG.
22, each of the base station devices may transmit, from each of the
reception antennas 12, the uplink reference signal for the
communication quality measurement in the uplink. By receiving the
uplink reference signal from each of the base station devices, the
mobile station 60 may measure the communication quality of each of
the uplinks between each of the base station devices and the mobile
station 60. Therefore, each of the base station devices may include
the components illustrated in FIG. 14, and the mobile station 60
may include the components illustrated in FIG. 15.
Next, description will be made of other embodiments of the radio
communication system. FIG. 23 is a configuration example of a fifth
embodiment of the radio communication system. The radio
communication system 1 includes the base station device 10-1, the
adjacent base station device 10-2, and the plurality of mobile
stations 60. Each of the base station device 10-1 and the adjacent
base station device 10-2 transmits the downlink reference signal to
the mobile station 60. Based on the reception quality of the
received downlink reference signal, the mobile station 60
determines whether or not handover occurs in the cell boundary
between the arrangement cell of the base station device 10-1 and
the arrangement cell of the adjacent base station device 10-2.
If the handover occurs, the mobile station 60 reports handover
information indicating that the handover occurred to a handover
base station device 10-1 and the adjacent base station device 10-2.
Moreover, the mobile station 60 transmits the uplink reference
signal. By receiving the uplink reference signal, the base station
device 10-1 measures a communication quality of the uplink between
the base station device 10-1 and the mobile station 60. In
substantially the same manner, the adjacent base station device
10-2 measures the communication quality of the uplink between the
adjacent base station device 10-2 and the mobile station 60.
FIG. 24 is a diagram illustrating a configuration example of the
mobile station 60 illustrated in FIG. 23. Reference numeral 66
indicates a handover information transmission unit. The same
components as in FIG. 18 have the same reference numerals that are
used in FIG. 18. The mobile station 60 includes the transmission
antenna 61, the reception antenna 62, the downlink communication
quality measuring unit 63, the downlink communication cell deciding
unit 64, the uplink reference signal transmission unit 65, and the
handover information transmission unit 66.
The downlink communication cell deciding unit 64 determines whether
or not the mobile station 60 performs the handover processing based
on the reception quality of the downlink. If the handover occurs,
the handover information transmission unit 66 transmits, to the
handover base station device 10-1 and the adjacent base station
device 10-2, the handover information indicating that the handover
occurred. Instead of transmitting the handover information to the
handover base station device 10-1 and the adjacent base station
device 10-2, the handover information transmission unit 66 may
transmit the handover information to either of the base station
device of the handover source and the base station device of the
handover destination. At this time, the above-described base
station device, which received the handover information, may
report, that the handover occurred in the mobile station 60 to the
other base station device through the inter-base station
communication. The handover information may include, for example,
the identifier of the mobile station 60 or the identifier of the
cell having the cell boundary in which the handover occurred.
FIG. 25 is a diagram illustrating a configuration example of the
base station device 10-1 illustrated in FIG. 23. Reference numeral
25 indicates a handover information acquiring unit. The same
components as in FIG. 19 have the same reference numerals that are
used in FIG. 19. The base station device 10-1 includes the
transmission antenna 11, the reception antenna 12, the tilt angle
changing units 13 and 14, the tilt angle control unit 15, the
downlink reference signal transmission unit 16, the inter-base
station communication unit 18, the uplink communication quality
measuring unit 20, and the handover information acquiring unit 25.
The inter-base station communication unit 18 includes the adjacent
cell communication quality acquiring unit 19.
The handover information acquiring unit 25 receives handover
information transmitted from the mobile station 60. If the handover
occurs, the uplink communication quality measuring unit 20 measures
the communication quality of the uplink between the base station
device 10-1 and the mobile station 60. The inter-base station
communication unit 18 transmits the uplink communication quality
information, which is generated by the uplink communication quality
measuring unit 20, to the adjacent base station device 10-2. The
adjacent cell communication quality acquiring unit 19 receives the
uplink communication quality information that is generated by the
uplink communication quality measuring unit 20 of the adjacent base
station device 10-2 and is then transmitted from the adjacent base
station device 10-2. The uplink communication quality information
generated by the uplink communication quality measuring unit 20 and
the uplink communication quality information acquired by the
adjacent cell communication quality acquiring unit 19 are output to
the tilt angle control unit 15.
The tilt angle control unit 15 decides the adjustment amount of the
tilt angle of the reception antenna 12 to decrease the difference
between the communication quality of the uplink between the
communication device 50 and the base station device 10-1 and the
communication quality of the uplink between the communication
device 50 and the adjacent base station device 10-2. The tilt angle
changing unit 14 mechanically or electrically changes the tilt
angle of the reception antenna 12 based on the adjustment amount
decided by the tilt angle control unit 15. For example, if the
communication quality of the uplink between the communication
device 50 and the base station device 10-1 is higher than the
communication quality of the uplink between the communication
device 50 and the adjacent base station device 10-2, the tilt angle
control unit 15 decides the adjustment amount to increase the tilt
angle of the reception antenna 12. If the communication quality of
the uplink between the communication device 50 and the adjacent
base station device 10-2 is higher than the communication quality
of the uplink between the communication device 50 and the base
station device 10-1, the tilt angle control unit 15 decides the
adjustment amount to decrease the tilt angle of the reception
antenna 12. The configuration of the tilt angle control unit 15 is
substantially the same as the configuration described above with
reference to FIG. 6.
Moreover, the tilt angle control unit 15 may control the tilt angle
of the transmission antenna 11. For example, the communication
quality of the uplink between the communication device 50 and the
base station device 10-1 is higher than the communication quality
of the uplink between the communication device 50 and the adjacent
base station device 10-2, the tilt angle control unit 15 determines
the adjustment amount of the tilt angle of the transmission antenna
11 to decrease the tilt angle of the transmission antenna 11. If
the communication quality of the uplink between the communication
device 50 and the adjacent base station device 10-2 is higher than
the communication quality of the uplink between the communication
device 50 and the base station device 10-1, the tilt angle control
unit 15 determines the adjustment amount to increase the tilt angle
of the transmission antenna 11. Adjusting the tilt angle of the
transmission antenna 11 may prevent to change the boundary of the
uplink drastically.
FIG. 26 is an explanation diagram of a control example of a tilt
angle of an antenna in the radio communication system illustrated
in FIG. 23.
In Operation FA, the downlink reference signal transmission unit 16
of the base station device 10-1 and the other base station devices
including the adjacent base station device 10-2 transmit the
downlink reference signal. In Operation FB, the downlink
communication quality measuring unit 63 of the mobile station 60
measures the reception quality of each of the downlinks between
each of the base station devices and the mobile station 60.
In Operation FC, the downlink communication quality measuring unit
63 determines whether or not the handover occurs in the cell
boundary between the arrangement cell of the base station device
10-1 and the arrangement cell of the adjacent base station device
10-2. If the handover does not occur (N in Operation FC), the
processing ends. If the handover occurs (Y in Operation FC), the
process goes to Operation FD. In Operation FD, the mobile station
60 performs the handover processing. At this time, the handover
information transmission unit 66 of the mobile station 60 reports
the handover information indicating that the handover occurred to
the base station device 10-1 and the adjacent base station device
10-2.
In Operation FF, the uplink reference signal transmission unit 65
of the mobile station 60 transmits the uplink reference signal. In
Operation FF, the uplink communication quality measuring unit 20 of
the base station device 10-1 and the adjacent base station device
10-2 measures the communication quality of each of the uplinks
between the base station device 10-1 and the mobile station 60 and
between the adjacent base station device 10-2 and the mobile
station 60.
In Operation FG, the inter-base communication unit 18 of the base
station device 10-1 transmits, to the adjacent base station device
10-2, the uplink communication quality information, generated by
the uplink communication quality measuring unit 20. Moreover, the
adjacent cell communication quality acquiring unit 19 of the base
station device 10-1 receives the uplink communication quality
information transmitted from the adjacent base station device
10-2.
In Operation FH, the tilt angle control unit 15 of the base station
device 10-1 determines whether the difference of the communication
quality of each of the uplinks between the base station device 10-1
and the mobile station 60 and between the adjacent base station
device 10-2 and the mobile station 60 is smaller than or equal to a
threshold value T4. If the difference of the communication quality
is smaller than or equal to the threshold value T4 (Y in Operation
FH), the processing ends. If the difference of the communication
quality is not smaller than or equal to a threshold value T4 (N in
Operation FH), the process goes to Operation FI.
In Operation FI, the tilt angle control unit 15 determines whether
or not the communication quality between the base station device
10-1 and the mobile station 60 is higher than the communication
quality between the adjacent base station device 10-2 and the
mobile station 60. If the communication quality between the base
station device 10-1 and the mobile station 60 is higher than the
communication quality between the adjacent base station device 10-2
and the mobile station 60 (Y in Operation FI), the process goes to
Operation FJ. If the communication quality between the base station
device 10-1 and the mobile station 60 is not higher than the
communication quality between the adjacent base station device 10-2
and the mobile station 60 (N in Operation FI), the process goes to
Operation FK.
In Operation FJ, the adjustment amount deciding unit 32 decides the
adjustment amount to decrease the tilt angle of the transmission
antenna 11. Furthermore or instead, the adjustment amount deciding
unit 32 decides the adjustment amount to increase the tilt angle of
the reception antenna 12. In Operation FK, the adjustment amount
deciding unit 32 decides the adjustment amount to increase the tilt
angle of the transmission antenna 11. Furthermore or instead, the
adjustment amount deciding unit 32 decides the adjustment amount to
decrease the tilt angle of the reception antenna 12. The tilt angle
changing unit 13 changes the tilt angle of the transmission antenna
11 based on the decided adjustment amount. Furthermore or instead,
the tilt angle changing unit 14 changes the tilt angle of the
reception antenna 12 based on the decided adjustment amount. After
Operation FJ or Operation FK, the processing ends.
According to the present embodiment, the mobile station 60 in which
the handover occurs is in the cell boundary of the downlink, which
makes it possible to control each tilt angle of the transmission
antenna 11 and the reception antenna 12 based on the uplink
communication quality of each of the uplinks between each of the
base station devices and the mobile station 60 that are adjacent
each other.
As with the embodiments described with reference to FIG. 13 to FIG.
16, in the embodiments described with reference to FIG. 23 to FIG.
26, each of the base station devices may transmit, from each of the
reception antennas 12 thereof, the uplink reference signal for the
communication quality measurement of the uplink. By receiving the
uplink reference signal from each of the base station devices, the
mobile station 60 may measure the communication quality of each of
the uplinks between each of the base station devices and the mobile
station 60. Therefore, the base station device 10-1 and the
adjacent base station device 10-2 may include the components
illustrated in FIG. 14, and the mobile station 60 may include the
components illustrated in FIG. 15.
All examples and conditional language recited herein are intended
for pedagogical purposes to aid the reader in understanding the
principles of the invention and the concepts contributed by the
inventor to furthering the art, and are to be construed as being
without limitation to such specifically recited examples and
conditions, nor does the organization of such examples in the
specification relate to a showing of the superiority and
inferiority of the invention. Although the embodiment(s) of the
present invention(s) has(have) been described in detail, it should
be understood that the various changes, substitutions, and
alterations could be made hereto without departing from the spirit
and scope of the invention.
* * * * *